Periodontitis is a prevalent chronic inflammatory disease that leads to the destruction of the tissues that surround and support the teeth (periodontium). This oral disease is initiated by bacterial biofilms, which form on subgingival tooth surfaces and comprise mostly communities of gram-negative anaerobic species. The host inflammatory response to chronic microbial challenge at the dentogingival niche is implicated in inflicting damage upon the periodontium.
Although traditionally perceived as an antimicrobial enzyme system in serum, complement is now recognized as a central component of host defense impacting both innate and adaptive immunity. Not surprisingly, given its importance in fighting pathogens, complement constitutes a key target of immune evasion by microbes that cause persistent infections.